JP2016211053A - Copper alloy excellent in heat resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Cu-Fe-P-based copper alloy having high strength, high conductivity and further excellent in heat resistance.SOLUTION: There is provided a copper alloy containing, by mass%, Fe:1.8 to 2.7%, P:0.01 to 0.20%, Zn:0.01 to 0.30%, Sn:0.01 to 0.2% and the balance copper with inevitable impurities, having a compound with circle equivalent diameter of over 1 μm of 0 to 5.0×10per observation visual field of 1 mmand a compound with circle equivalent diameter of 100 to 200 nm of 1.0×10to 1.0×10per observation visual field of 1 mm.SELECTED DRAWING: None

Description

  The present invention relates to a copper alloy, and in particular, to a copper alloy having high strength, high conductivity, and excellent heat resistance.

  A copper alloy is used as the material of the semiconductor lead frame. As a copper alloy, a Cu—Fe—P-based copper alloy containing Fe and P is generally used. As the Cu-Fe-P-based copper alloy, CDA194 alloy can be exemplified. Specifically, Fe: 2.1 to 2.6 mass%, P: 0.015 to 0.15 mass%, Zn: 0 A copper alloy containing 0.05 to 0.20 mass% with the balance being Cu and inevitable impurities. Cu-Fe-P-based copper alloys have high strength, good conductivity, and excellent thermal conductivity by precipitating intermetallic compounds such as Fe or Fe-P in the matrix It becomes. Therefore, it is widely used as an international standard alloy.

  In recent years, as the capacity, size, thickness, weight, and functionality of semiconductor devices used in electronic devices have increased, lead frames used in semiconductor devices have become smaller in cross-sectional area, resulting in greater strength and conductivity. Thermal conductivity is required. Accordingly, copper alloy plates used for lead frames used in these semiconductor devices are also required to have higher strength, higher conductivity, and better thermal conductivity.

  For example, Patent Document 1 discloses a technique for improving the strength, conductivity, bending workability, and stress relaxation resistance of a copper alloy plate for electrical and electronic parts. According to this technique, the strength of the copper alloy plate is obtained by forming a two-phase structure in which a relatively large amount of Fe is contained and 2.5 to 3.5% by mass and second phase particles are precipitated in the Cu matrix. And the conductivity is increased.

  However, if the Fe content is too high, the conductivity may deteriorate instead. In order to improve the electrical conductivity, for example, the precipitation amount of precipitated particles such as Fe or Fe—P may be increased. However, it is known that increasing the amount of precipitated particles causes growth and coarsening of the precipitated particles, resulting in a decrease in strength and heat resistance.

  When the Cu—Fe—P copper alloy plate is processed into a lead frame or the like, it is generally formed into a multi-pin shape by stamping (sometimes referred to as press punching). Recently, as described above, in order to cope with the reduction in size and thickness and weight of semiconductor devices used in electronic equipment, the thickness of copper alloy plates used as raw materials and the increase in the number of pins of lead frames and the like are progressing. Along with this, strain stress tends to remain in the processed product after the stamping process, and the pins tend to be uneven. Therefore, the multi-pin copper alloy plate obtained by stamping is usually subjected to heat treatment such as strain relief annealing to remove the strain. However, when such heat treatment is performed, the material is easily softened, and the strength before the heat treatment cannot be maintained. Further, in order to improve productivity, the heat treatment is required to be performed at a higher temperature and in a shorter time, and heat resistance capable of maintaining high strength after the heat treatment at a high temperature is strongly required.

  Moreover, the technique which improves the intensity | strength, electroconductivity, and heat resistance of a copper alloy is disclosed by patent documents 2-4.

Patent Document 2, Cu in the Fe precipitates dispersed in the matrix phase, the area ratio S ₁ total area of the deposit area is less than 20 nm ² or more 200 nm ² is a percentage of the total Cu matrix Is 0.4% or more, and the area ratio S _2, which is the ratio of the total area of precipitates having an area of 200 nm ² or more to the entire Cu matrix, is 0.4 ≦ S ₁ / S ₂ ≦ 1. A technique for improving strength, conductivity, and heat resistance by satisfying the relationship 4 is disclosed.

  Patent Document 3 discloses a fine Fe-based compound that effectively suppresses coarse Fe-based compounds of 0.1 μm or more separated by a filter having an aperture size of 0.1 μm by the extraction residue method and effectively contributes to improvement in strength. A technique for increasing the strength, conductivity, and heat resistance by increasing the ratio is disclosed.

Patent Document 4 discloses that the density of Fe-P particles having a particle size of 1 μm or more is 30 particles / mm ² or less, thereby increasing the density of γFe particles and αFe particles to increase strength, conductivity, and heat resistance. Technology is disclosed.

  Although it is not a technique for improving the strength, electrical conductivity, and heat resistance of a copper alloy, Patent Document 5 describes the presence in crystal grains and in grain boundaries in a cross section perpendicular to the casting direction after continuous casting. A technique for reducing the number of surface defects, internal cracks, and the like in a copper alloy sheet as a product by setting the average value of the major axis of primary iron particles to 5 μm or less is disclosed.

JP 2012-207261 A Japanese Patent No. 5555154 Japanese Patent No. 4950584 JP 2014-55341 A JP 2013-71155 A

  In the technique of Patent Document 1, the strength and conductivity of the copper alloy plate are increased, but heat resistance is not considered.

  In the technique of Patent Document 2, very fine precipitates having a diameter of several nm to several tens of nm are deposited. In the techniques of Patent Documents 3 to 5, an Fe-based compound having a diameter of 0.1 μm or more is formed. Its presence ratio and size are controlled with attention. However, as a result of studies by the present inventors, in Patent Documents 2 to 5, the relationship between the number density of compounds having an equivalent circle diameter of 100 to 200 nm, strength, conductivity, and heat resistance has not been studied.

  The present invention has been made paying attention to the above-described circumstances, and its object is to provide a Cu—Fe—P-based copper alloy having high strength, high conductivity, and excellent heat resistance. There is.

The copper alloy excellent in heat resistance according to the present invention that has solved the above problems is mass%, Fe: 1.8 to 2.7%, P: 0.01 to 0.20%, Zn: 0. A copper alloy containing 0.01 to 0.30%, Sn: 0.01 to 0.2%, with the balance being copper and inevitable impurities. The circle-equivalent compound of 1μm than the observation field area 1 mm ² per zero or more 5.0 × 10 ³ or less in diameter, the compounds of 100~200nm equivalent circle diameter observed field area 1 mm ² per 1.0 × The point is that it is 10 ^{5 to} 1.0 × 10 ⁷ . Hereinafter, for chemical components,% means mass%.

  The copper alloy may further contain, in mass%, one or more selected from the group consisting of Si, Ni, and Co: 0.01 to 0.1% in total.

  According to the present invention, since the component composition and the number density of the compound of a predetermined size are appropriately controlled, Cu—Fe—P-based copper having high strength, high conductivity, and excellent heat resistance. Can provide alloys.

The present inventor has intensively studied to provide a Cu—Fe—P-based copper alloy having high strength, high conductivity, and excellent heat resistance. As a result, the component composition of the copper alloy is appropriately controlled, and among the compounds contained in the copper alloy, (A) 0 or more 5.0 × compounds per 1 mm ^{2 of} the observation visual field area of an equivalent circle diameter of more than 1 μm. 10 ³ or less, and (B) a compound having an equivalent circle diameter of 100 to 200 nm of 1.0 × 10 ^{5 to} 1.0 × 10 ⁷ per 1 mm ^{2 of} the viewing field area, the strength, conductivity, and The present invention has been completed by finding that a copper alloy having excellent heat resistance can be realized.

  In addition, the copper alloy according to the present invention can be hot-rolled after melting and casting the copper alloy with adjusted component composition, soaking the obtained ingot, and in particular, controlling the number density of the compound within the above range. In order to achieve this, it has become clear that the conditions for soaking and hot rolling should be adjusted appropriately.

  Hereinafter, the present invention will be described in detail.

(A) Number density of compounds with equivalent circle diameter of more than 1 μm In the copper alloy of the present invention, the number of compounds with equivalent circle diameter of more than 1 μm is 0 or more and 5.0 × 10 ³ or less per 1 mm ^{2 of} the viewing field area. . When the number density of the compound having an equivalent circle diameter of more than 1 μm exceeds 5.0 × 10 ³ pieces / mm ² , the equivalent of a circle having an equivalent circle diameter of 100 to 200 nm, which will be described later, and a circle formed by primary annealing or secondary annealing The production amount of a compound having a diameter of several nm to several tens nm is reduced. As a result, strength, conductivity, and heat resistance deteriorate. Moreover, it becomes a cause which a crack generate | occur | produces at the time of press punching. Therefore, in the present invention, the number density of compounds having an equivalent circle diameter of more than 1 μm is set to 5.0 × 10 ³ pieces / mm ² or less. The number density of compounds having an equivalent circle diameter of more than 1 μm is preferably 4.5 × 10 ³ pieces / mm ² or less, more preferably 4.0 × 10 ³ pieces / mm ² or less. The number density of compounds having an equivalent circle diameter of more than 1 μm is preferably as small as possible, and most preferably 0 / mm ² .

(B) Number density of compound having an equivalent circle diameter of 100 to 200 nm In the copper alloy of the present invention, a compound having an equivalent circle diameter of 100 to 200 nm is 1.0 × 10 ⁵ or more per 1 mm ^{2 of} the observation visual field area. × 10 ⁷ or less. That is, the number of compounds having an equivalent circle diameter of 100 to 200 nm is 0.10 × 10 ⁶ or more and 10 × 10 ⁶ or less. A compound having an equivalent circle diameter of 100 to 200 nm has not been particularly noticed in the past, but the present inventors have examined it for the first time and contributed to improving the conductivity and heat resistance of the copper alloy. In order to exert such an effect, the number density of the compound having a circle equivalent diameter of 100 to 200 nm is set to 1.0 × 10 ⁵ or more. The number density of compounds having an equivalent circle diameter of 100 to 200 nm is preferably 5.0 × 10 ⁵ pieces / mm ² or more. However, when the number density of the compound having a circle equivalent diameter of 100 to 200 nm becomes too large, the amount of the compound of several nm to several tens of nm generated by the primary annealing and the secondary annealing is reduced, and the strength of the copper alloy is reduced. The heat resistance also deteriorates. Therefore, the number density of a compound having an equivalent circle diameter of 100 to 200 nm needs to be 1.0 × 10 ⁷ or less. The number density of the compound having an equivalent circle diameter of 100 to 200 nm is preferably 8.0 × 10 ⁶ pieces / mm ² or less, more preferably 5.0 × 10 ⁶ pieces / mm ² or less.

  The number density of a compound having a circle equivalent diameter of more than 1 μm and a compound having a diameter of 100 to 200 nm may be measured by the following procedure. That is, the number density of the compound having an equivalent circle diameter of more than 1 μm is, for example, in the cross section in the width direction of the test piece, for example, a region of 90 μm in the thickness direction at the center of the plate thickness × 125 μm in the cross section direction with a scanning electron microscope. The circle equivalent diameter of each compound is calculated using image analysis software, and the number of compounds having an equivalent circle diameter of more than 1 μm is obtained and divided by the observation visual field area.

  The number density of a compound having an equivalent circle diameter of 100 to 200 nm is, for example, a region of 9.0 μm in the thickness direction at the center of the plate thickness × 12.5 μm in the cross-sectional direction in the cross section, at a magnification of 10,000. Observe and calculate the equivalent circle diameter of each compound using image analysis software in the same manner as described above, obtain the number of compounds having an equivalent circle diameter of 100 to 200 nm, and divide by the observation visual field area. The type of compound to be analyzed is not particularly limited.

  As the image analysis software, for example, Image-Pro Plus manufactured by Macromedia can be used.

In the technique disclosed in Patent Document 3, as described above, coarse Fe-based compounds of 0.1 μm or more separated by a filter having an aperture size of 0.1 μm are suppressed by the extraction residue method. . However, with this technique, as in the present invention, the number density of a compound having a circle equivalent diameter of more than 1 μm and a compound having a diameter of 100 to 200 nm cannot be calculated separately. Patent Document 5 describes that the average value of the major axis of primary iron particles is suppressed to 5 μm or less, and Patent Document 4 describes that the density of Fe—P particles having a particle diameter of 1 μm or more is 30. It is described that the number is not more than pieces / mm ² . However, in Patent Documents 4 and 5, the number density of a compound having a circle equivalent diameter of 100 to 200 nm is not considered at all.

  In the copper alloy according to the present invention, it is important that the number density of the compound having an equivalent circle diameter of more than 1 μm and the number density of the compound having a diameter of 100 to 200 nm satisfy the above range. And Fe: 1.8 to 2.7%, P: 0.01 to 0.20%, Zn: 0.01 to 0.30%, Sn: 0.01 to 0.2% must be satisfied. is there.

  Fe is an element necessary for improving strength and heat resistance by forming a solid solution in a parent phase of a copper alloy or generating an Fe-based compound. If the amount of Fe is less than 1.8%, the amount of solid solution or precipitation of Fe is insufficient, and strength and heat resistance cannot be obtained. Therefore, in the present invention, the amount of Fe is 1.8% or more. The amount of Fe is preferably 2.1% or more. However, when the amount of Fe is excessive, a coarse Fe compound is generated, which causes cracks during punching. Therefore, in the present invention, the amount of Fe is set to 2.7% or less. The amount of Fe is preferably 2.6% or less, more preferably 2.4% or less.

  P is an element having an action of deoxidizing oxygen mixed in the molten metal, and is an element that forms a compound with Fe to improve the strength and heat resistance of the copper alloy. In order to exert such an effect, the amount of P needs to be 0.01% or more. The amount of P is preferably 0.02% or more. However, when the amount of P becomes excessive, the conductivity decreases. Moreover, hot workability falls. Therefore, in the present invention, the P content is 0.20% or less. The amount of P is preferably 0.15% or less.

  Zn is an element necessary for improving the heat-resistant peelability of the solder with respect to the copper alloy or for improving the heat-resistant peelability of the Sn plating with respect to the copper alloy. Such heat peelability is a characteristic required when, for example, a copper alloy is used for a lead frame or the like. In order to exert such an effect, the Zn content needs to be 0.01% or more. The amount of Zn is preferably 0.05% or more. However, when the amount of Zn becomes excessive, the conductivity decreases. Moreover, the wettability of the solder with respect to a copper alloy falls. Therefore, in the present invention, the Zn content is set to 0.30% or less. The amount of Zn is preferably 0.20% or less.

  Sn is an element necessary for improving the strength and heat resistance of the copper alloy. In order to exert such an effect, the Sn amount is set to 0.01% or more. The amount of Sn is preferably 0.02% or more. However, when the amount of Sn becomes excessive, the conductivity decreases. Moreover, hot workability also falls. Therefore, in the present invention, the Sn amount is 0.2% or less. Sn amount becomes like this. Preferably it is 0.10% or less, More preferably, it is 0.05% or less.

  The balance of the copper alloy according to the present invention is copper and inevitable impurities.

  The copper alloy of the present invention may further contain 0.01 to 0.1% in total of one or more selected from the group consisting of Si, Ni, and Co in mass%.

  Si, Ni, and Co are elements that form a compound with Fe or P and improve the strength and heat resistance of the copper alloy. In order to effectively exert such an action, it is preferable that Si, Ni, and Co be selected from one or more of two or more kinds in total to 0.01% or more, and more preferably 0.03% or more. . However, when an element such as Si is excessively contained, the compound becomes coarse and causes cracks during press punching. Therefore, in the present invention, it is preferable that Si, Ni, and Co are selected from one or two or more, and the total is preferably 0.1% or less, and more preferably 0.08% or less.

  The copper alloy according to the present invention has a tensile strength of 530 MPa or more, an electrical conductivity of 60% IACS or more, and a Vickers hardness of 155 Hv or more. Further, after annealing at 475 ° C. for 1 minute, the Vickers hardness is 140 Hv or more, and a copper alloy having excellent heat resistance is obtained.

  Next, preferable production conditions for the copper alloy according to the present invention will be described.

  First, a copper alloy with an adjusted component composition is melted and cast, and the resulting ingot is soaked and then hot rolled. In order to control the number density of the compound within the above range, the soaking condition and the hot rolling condition may be adjusted appropriately. The melting and casting of the copper alloy may be performed according to a conventional method.

  The soaking may be performed by heating the ingot to 800 ° C. or more and less than 950 ° C. and holding it for a certain time as necessary. The holding time is, for example, 10 to 120 minutes. When the temperature of the soaking is below 800 ° C., a large number of compounds having an equivalent circle diameter of 100 to 200 nm are generated, and the number density tends to be high. Therefore, in the present invention, the temperature of soaking is preferably 800 ° C. or higher. The temperature of soaking is more preferably 830 ° C. or higher, further preferably 850 ° C. or higher. However, when the temperature of soaking is 950 ° C. or higher, a large number of compounds having an equivalent circle diameter of more than 1 μm are formed, and the number density tends to increase. Therefore, in the present invention, the temperature of soaking is preferably less than 950 ° C. The temperature of soaking is more preferably 940 ° C. or lower, and further preferably 920 ° C. or lower. For example, in Patent Document 4, since the ingot is heated to 1020 to 1080 ° C. and held for 2 hours or more, it is considered that too many compounds having an equivalent circle diameter of more than 1 μm are generated. Therefore, in the said patent document 4, it is thought that intensity | strength is low.

  After soaking, hot rolling is performed. The rolling reduction of the hot rolling is not particularly limited, and may be determined based on the relationship between the target plate thickness and the cold rolling rate in the subsequent cold rolling. The hot rolling can be performed once or a plurality of times.

  When producing the copper alloy of the present invention, it is particularly recommended that the end temperature of hot rolling be 700 ° C. or more and less than 850 ° C. When the end temperature of hot rolling is lower than 700 ° C., a large number of compounds having an equivalent circle diameter of 100 to 200 nm are generated, and the number density tends to increase. Therefore, in the present invention, the end temperature of hot rolling is preferably 700 ° C. or higher. The end temperature of hot rolling is more preferably 730 ° C. or higher, and further preferably 750 ° C. or higher. However, when the end temperature of hot rolling is 850 ° C. or more, a large number of compounds having an equivalent circle diameter of more than 1 μm are generated, and the number density tends to increase. Therefore, in the present invention, the end temperature of hot rolling is preferably less than 850 ° C. The end temperature of hot rolling is more preferably 840 ° C. or lower, and further preferably 830 ° C. or lower.

  After hot rolling, it may be cooled rapidly to room temperature. When the cooling rate after hot rolling is low, a large amount of coarse compounds having an equivalent circle diameter of more than 1 μm are precipitated in the cooling process, and it becomes difficult to produce a predetermined amount of a fine compound having an equivalent circle diameter of 100 to 200 nm. In the present invention, the rapid cooling is cooling at an average cooling rate exceeding air cooling, and is preferably 20 ° C./second or more. The upper limit of the average cooling rate is not particularly limited, but is preferably about 500 ° C./second or less in consideration of actual operation and the like.

  The rapid cooling means is not particularly limited, and for example, a known cooling means such as water cooling can be adopted.

  After the rapid cooling, the first cold rolling (hereinafter referred to as primary cold rolling) is subjected to heat treatment by primary annealing and then the second cold rolling (hereinafter secondary cold rolling). Therefore, the strain in the copper alloy structure may be removed by forming into a predetermined shape and then performing heat treatment by secondary annealing.

  Although the rolling processing rate in primary cold rolling is arbitrary, what is necessary is just to adjust according to the plate | board thickness of a final board | plate material, and the rolling processing rate in the secondary cold rolling mentioned later.

  After the primary cold rolling, for example, by performing primary annealing at 450 to 650 ° C. for 30 minutes to 24 hours, the number density of compounds having an equivalent circle diameter of 100 to 200 nm can be controlled within an appropriate range. When the primary annealing temperature is less than 450 ° C. or the primary annealing time is less than 30 minutes, due to insufficient heat treatment, the number density of compounds having an equivalent circle diameter of 100 to 200 nm tends to be low, and the conductivity tends to be low. On the other hand, when the primary annealing temperature exceeds 650 ° C., the number density of compounds having an equivalent circle diameter of 100 to 200 nm tends to be high, and the strength tends to be low. On the other hand, when the primary annealing time exceeds 24 hours, energy loss occurs and it is economically inefficient.

  Next, after the primary annealing, secondary cold rolling is performed. By secondary cold rolling, processing strain can be introduced into the metal structure and the strength of the copper alloy sheet can be improved. The rolling rate in secondary cold rolling may be, for example, 25 to 70%. When the rolling ratio in secondary cold rolling is less than 25%, the amount of strain accumulated in the metal structure by rolling is reduced, and it becomes difficult to obtain sufficient strength. On the other hand, if the rolling rate in secondary cold rolling exceeds 70%, the strain amount accumulated in the metal structure is saturated, and it is difficult to obtain an improvement in strength.

  Next, after secondary cold rolling, it is preferable to perform secondary annealing at 250 to 450 ° C. for 20 to 1000 seconds. The secondary annealing is annealing for removing the strain introduced by the secondary cold rolling, and it is sufficient to remove the strain that moves in a low temperature range of 250 to 450 ° C. When the secondary annealing temperature is less than 250 ° C. or the secondary annealing time is less than 20 seconds, the removal of the movable strain becomes insufficient, and the conductivity tends to decrease. On the other hand, when the secondary annealing temperature exceeds 450 ° C. or the secondary annealing time exceeds 1000 seconds, the removal of strain becomes excessive and the strength tends to decrease.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, and may be implemented with modifications within a range that can meet the above and the gist described below. Of course, these are all possible and are included in the technical scope of the present invention.

  A copper alloy having the composition shown in Table 1 below, with the balance being copper and inevitable impurities, is melted in a coreless furnace, and then ingoted by a semi-continuous casting method, and is 70 mm thick × 200 mm wide × length long. A 500 mm ingot was produced. Table 1 below also shows the result of calculating the total amount of Si, Ni, and Co.

  After chamfering the surface of the obtained ingot, hot rolling was performed after carrying out soaking treatment that was held at a temperature of 750 to 1050 ° C. for 1 hour to obtain a hot-rolled sheet having a thickness of 15 mm. Table 2 below shows the temperature for soaking. The hot rolling start temperature was adjusted so that the hot rolling end temperature was 600 to 800 ° C., and immediately after the hot rolling was finished, it was rapidly cooled by water cooling. Table 2 below shows the hot rolling end temperature.

  Next, after removing the oxide scale, primary cold rolling, primary annealing, secondary cold rolling, and secondary annealing were performed to obtain a cold-rolled sheet having a thickness of 0.25 mm. The primary annealing was performed by heating to 550 ° C. and holding at this temperature for 4 hours. The secondary annealing was performed by heating to 350 ° C. and holding at this temperature for 60 seconds.

  About the obtained cold-rolled sheet, the number density, tensile strength, electrical conductivity, hardness, and heat resistance of the compound were measured.

  The number density of the compounds was measured for a compound having an equivalent circle diameter of more than 1 μm and a compound having an equivalent circle diameter of 100 to 200 nm.

  The number density of the compound having an equivalent circle diameter of more than 1 μm was measured with a scanning electron microscope at an observation magnification of 1000 × in a cross section in the width direction of the cold-rolled sheet in a thickness direction of 90 μm × 125 μm in the cross-sectional direction. The circle equivalent diameter of the compound in the observation field was measured using image analysis software (Image-Pro Plus manufactured by Macromedica). The measurement results are shown in Table 2 below.

  The number density of the compound having a circle-equivalent diameter of 100 to 200 nm is determined by using a scanning electron microscope in a cross section in the width direction of the cold-rolled sheet in an area of 9.0 μm in the thickness direction and 12.5 μm in the cross-sectional direction. The observation was performed at an observation magnification of 10,000 times, and the equivalent circle diameter of the compound in the observation field was measured using the image analysis software. The measurement results are shown in Table 2 below.

  Tensile strength was measured with a universal tester manufactured by Instron of Model 5882 using a JIS No. 13 B test piece cut out from the cold rolled sheet. The tensile strength was measured at room temperature, the test speed was 10.0 mm / min, and the distance between marked lines GL was 50 mm. The measurement results are shown in Table 2 below. In this example, the tensile strength of 530 MPa or more was regarded as acceptable.

  The electrical conductivity was calculated by an average cross-sectional area method using a test piece obtained by processing the cold-rolled sheet into a strip shape having a width of 10 mm and a length of 300 mm by milling, measuring the electrical resistance with a double bridge resistance measuring device. The calculation results are shown in Table 2 below. In the present invention, 60% IACS or higher was regarded as acceptable, and the electrical conductivity was evaluated as good.

  The hardness was measured at three locations by applying a load of 0.5 kg using a micro Vickers hardness meter (trade name “micro hardness meter”) manufactured by Matsuzawa Seiki Seisakusho, and the average value was obtained. The calculation results are shown in Table 2 below. In this example, the hardness was 155 Hv.

  A case where the tensile strength was 530 MPa or more and the hardness was 155 Hv or more was evaluated as high strength, and an invention example was obtained. On the other hand, the case where at least one of the tensile strength and the hardness did not reach the acceptance standard was taken as a comparative example.

  For heat resistance, the cold-rolled sheet was simulated by annealing and heated at 475 ° C. for 1 minute, and then a micro Vickers hardness meter (trade name “micro hardness meter”) manufactured by Matsuzawa Seiki Seisakusho was used. A load was applied to measure the hardness. The measurement results are shown in Table 2 below. In the present invention, 140Hv or more was regarded as acceptable and evaluated as having excellent heat resistance.

  It can be considered as follows from Table 2 below.

  No. Nos. 1 to 8 are examples satisfying the requirements defined in the present invention, and the number density of a compound whose component composition is appropriately controlled and whose equivalent circle diameter exceeds 1 μm and whose equivalent circle diameter is 100 to 200 nm. Satisfying the predetermined conditions, a copper alloy having high strength, good conductivity and excellent heat resistance was obtained.

  No. 11 to 18 are examples that do not satisfy any of the requirements defined in the present invention.

  Specifically, no. No. 11 is an example in which the number density of the compound having an excessive amount of Fe and an equivalent circle diameter of more than 1 μm is too high. As a result, the conductivity decreased.

  No. No. 12 is an example in which the amount of Fe is too small, the tensile strength and hardness are low, and the heat resistance cannot be improved.

  No. No. 13 is an example in which the amount of P is excessive, and the number density of the compound having an equivalent circle diameter of more than 1 μm is too high. As a result, the tensile strength, hardness and electrical conductivity were low, and the heat resistance could not be improved.

  No. No. 14 is an example in which the amount of Sn is excessive, and the electrical conductivity decreased.

  No. No. 15 was soaked at 980 ° C. higher than the temperature range recommended in the present invention. As a result, the number density of the compound having an equivalent circle diameter of more than 1 μm became too high, and the heat resistance could not be improved.

  No. No. 16 was soaked at 1050 ° C. higher than the temperature range recommended in the present invention, and hot rolling was finished at 600 ° C. lower than the temperature range recommended in the present invention. As a result, the number density with an equivalent circle diameter of 100 to 200 nm was too high, and the tensile strength and hardness were low.

  No. No. 17 finished hot rolling at 670 ° C. lower than the temperature range recommended in the present invention. As a result, the number density with an equivalent circle diameter of 100 to 200 nm was too high, and the tensile strength and hardness were low.

  No. No. 18 performed soaking at 750 ° C. lower than the temperature range recommended in the present invention, and finished hot rolling at 650 ° C. lower than the temperature range recommended in the present invention. As a result, the number density with an equivalent circle diameter of 100 to 200 nm was too high, the tensile strength and hardness were lowered, and the heat resistance could not be improved.

Claims (2)

% By mass
Fe: 1.8 to 2.7%,
P: 0.01-0.20%,
Zn: 0.01-0.30%
Sn: contains 0.01 to 0.2%,
The balance is a copper alloy consisting of copper and inevitable impurities,
The number of compounds with an equivalent circle diameter of more than 1 μm is 0 or more and 5.0 × 10 ³ or less per 1 mm ^{2 of the} viewing field area.
A copper alloy excellent in heat resistance, characterized in that the number of compounds having an equivalent circle diameter of 100 to 200 nm is 1.0 × 10 ^{5 to} 1.0 × 10 ⁷ per 1 mm ^{2 of the} observation visual field area. Furthermore, in mass%,
The copper alloy according to claim 1, comprising one or more selected from the group consisting of Si, Ni, and Co: 0.01 to 0.1% in total.